The base boost from Anubis when stating 100% Dark Attack is a base of 80% plus 4% per Dark Eidolon in your subs. There are 5 sub slots which will work to a full 20% when all 5 sub slots are filled with Dark Eidolon. (Your support main slot does not affect your Anubis and conversely when using an Anubis in support; only the sub slots can give you a bonus).
Each limit break adds 5% to the base value and doesn't affect the increase from Dark Eidolons in the sub slots (still 4% per Dark Eidolon in a sub slot).
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